Introduction


Are You Human or Are You Microbe?

Recent studies have shown that the human body contains about 100 trillion cells, but only maybe one in ten of those cells is actually human. The rest of the cells are bacteria, viruses, and other microorganisms living on and in us. You could say, we are more “microbe” than we are “human.”

You can learn more about this microbe discovery by listening to the podcast (or reading the transcript) of the NPR article Finally, A Map Of All The Microbes On Your Body.

icon of a human head composed of microbes

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Immune Cells in Action

We rely on these microorganisms to survive; it’s a type of symbiotic relationship. But, there are microorganisms that can harm us. Our immune system protects us from these pathogenic types of microbes.  The white blood cells are essential players in this protection.  

You can view a cell being attacked by a pathogenic virus and see an animation of how the body responds in the video Immune Cells in Action (1:40) below.

Open Immune Cells in Action in a new tab

Now, let’s get to know our white blood cells a little more closely.

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Lesson Objectives

Following successful completion of this lesson, students will be able to...

  • Distinguish between the five major categories of white blood cells and their functions.
  • Explain how two major types of lymphocytes are formed, activated, and function in the immune system.

Enduring Understandings

  • The immune/lymphatic system is composed of lymphatic organs and white blood cells that work together to fight pathogenic organisms.
  • Disorders and diseases of the immune system are a result of disruption of the homeostatic mechanisms within the immune system.

The above objectives correspond with the Alabama Course of Study: Anatomy and Physiology standards: 12, 12a, and 12b

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